Coastal Storm Update

A storm with a long history of dumping snow and causing severe weather is preparing to move into the Atlantic Ocean.  This storm is already the biggest in two years across much of the Midwest and Ohio Valley and DC will join the party when all is said and done.  Thanks to a little snowstorm in February New England is likely to be excluded from that club but none the less the forecast/discussion.

Current Conditions
Temperatures on average are around 35 degrees in MA/CT/RI.

5 am 2 m Temps (image weatherbell)

The surface chart shows low pressure on the eastern NC coast

WPC Surface Analysis 520 AM

The Northeast radar is picking up a nice slug of moisture in the VA/MD/PA/DE/NJ region

NWS Northeast Regional Radar 558 AM

The water vapor imagery shows an impressive storm about to hit the water

NOAA GOES_E water vapor sat imagery 515 am

That dry slot show in Delaware should fill in as the low center begins to deepen.  It will pull moisture into its center and a dry slot further west will develop.

Forecast

Today is alright in Southern New England.  Temperatures will max around 35 in MA, 40 in RI/CT

10z RAP 2 m T valid 2 PM (image weatherbell)

Skies will remain overcast and winds will steadily increase out of the ENE, then NE.  I cannot rule out isolated rain and snow showers during daylight hours on Wednesday.  However I do not expect them to do much and the bulk of the storm arrives after midnight.  Temperatures at 11 PM

10z RAP 2 m T 11 PM (image weatherbell)

It will be cold enough to support all snow.  Winds at 4 AM

06z NAM 10 m winds (image weatherbell)

Winds at 900 mb, same time

00z NAM Hires 900 mb winds, mslp (image weatherbell)

Combine this with expected snow totals by 7 am tomorrow of 3-6 inches and there will be power outages early.   Here is the NAM high resolution snow totals by 7 am Thursday

00z NAM Hires snow totals (image weatherbell)

There is some disagreement- some models want to shoot the storm south and due east.  Which I am fine with- I do not think that is unreasonable.  In any other normal nor'easter that would greatly lessen the impacts.  This isn't a normal nor'easter, it has a large wind field and it is staring a major block in the face to its Northeast.  There is also energy at the 500 mb level moving through Southern Canada.  Its interaction will drive snow accumulations, not the ocean storm.  NAM by Thursday evening

00z NAM hires snow total Thur 7 PM (image weatherbell)

Thats getting close to 20 inches of snow in RI, Southern Worcester, and Norfolk counties.  Southeastern MA is a wildcard as well.  This lasts into Friday afternoon for some, especially Western MA/CT.  Here is my map.

MY FORECAST

These could go way up in the NAM is correct.  I will update this afternoon, have a good day

Winter Storm Watch Posted

The National Weather Service in Taunton has issued a Winter Storm Watch for all of Southeastern New England.

NWS Boston Watches and Warnings

The EURO is on board for a major strike.  High winds, coastal flooding, and extreme beach erosion will reshape the eastern shoreline which is still recovering from the Blizzard (and other battering storms recently).

Questions remain as to how effective snow will be able to accumulate.  Seeing signs there will be no problem in Central MA, Northern RI, NE CT.  This also extends to Norfolk County.

Tomorrow is overcast with increasing wind.  Light snow may break out as energy is pulled into the storm.  Bulk of the action begins working in by 8-9 and should reach the MA/RI/CT border by midnight.  From there moderate to heavy snow develops and stays around until Friday morning.

Winds will be strong and combined with heavy wet snow this will lead to scattered power outages.

A full update with snowfall accumulation map will be posted by 7 am.

There Will Be Snow, Wind. How Much and When?

A good portion of Southern New England will be impacted by a winter storm Wednesday thru Friday.  In the fantasy world of numerical weather prediction (models) the American GFS looks like it has scored a big upset; the EURO has trended towards a major storm in the region which is why I am willing to make the call this morning.  There is still some uncertainty for SNE because the new and improved Canadian is on board for just a few inches of snow.  Let's break it down

Tuesday
Another day with a mix of sun and clouds.  Our old friend the Upper Level Low will slowly pull away but the key word is slowly.  Temperatures to start the morning are largely in the 20's

2 m temperatures 5 am EST (image weatherbell)

Temps will rebound to the low 40's for most, mid 40's in CT

09z RAP 2 m Temp 1 PM EST (image weatherbell)

Winds today will be less than yesterday (6-9 mph) and out of the north.  

Storm Discussion

This is technical- feel free to skip down to the forecast.

HPC surface chart 522 AM EST

A piece of energy from the Southwest and a Low pressure system from Western Canada will merge in the Ohio River Valley, occlude, and spawn a new low pressure center near the NC/VA line.  I've tried to illustrate the process above.  The system already has a lot of moisture

Upper MS Valley NWS regional radar 530 AM  EST

This system will be into Kentucky and spreading its effects North and East by 7 PM tonight

HPC forecast surface chart 7 PM EST

Now there are two scenario's.  First scenario is the large scale forcing takes over and allows the low to come further north as the American GFS shows.  Most likely the main center of the storm stays south of the 40/70 benchmark.  However it is so large and given the block and slow movement of storms in the North Atlantic vicinity there will be interactions bewteen the various systems.  I think the interaction between a low moving into Southern Canada on Thursday will enhance precipitation/snow for New England

Here is the GFS at 500 mb

00z GFS 500 mb vort valid Wednesday 7 PM

Here is the NAM 

00z NAM 500 mb vort valid Wednesday 7 PM

Here is the EURO at 48 and 72

00z EURO 500 mb heights Wed 7 PM (image weatherbell)

See the energy over the UP of Michigan?  

00z EURO 500 mb heights Thu 7 PM (image weatherbell)

That energy is now near Toronto on Thursday.  So that will be the battle.  All of the guidance indicates interactions at 500 mb so I am confident in several inches Thursday into Friday.   The EURO control is in line with the GFS, NAM, GEFS, JMA.  The op EURO is close...so going with a decent slug of snow tomorrow night through Friday.

STORM FORECAST

During the day Wednesday only light precipitation falls.  Any snow will not accumulate as we can expect surface temperatures to be running above freezing.  

00z EURO 2 m Temp max Wed PM (image weatherbell)

The heaviest precipitation begins by midnight south of the MA/RI/CT border.  Winds should begin to crank by then

00z NAM hires 900 mb winds Thursday 1 AM (image weatherbell)

These are over hurricane force just a few thousand feet up.  With the heavy precipitation expected one can expect these to mix to the surface at times, especially over the Cape.  The problem then becomes the stall.  With the block in place this storm will stall offshore.  This will allow precipitation to be heavy enough to accumulate during the day Thursday and will also devastate the eastern facing coast.  The Thursday morning high tide is likely the worst of the bunch.  Here is the total precipitation by Thursday morning

HPC 2 day precipitation totals

If we add a day look how much falls Thursday-Thursday night

HPC 3 day precipitation totals

With the winds sustained at 25-30 mph Thursday

06z NAM 10m winds, mslp Thu 7 am (image weatherbell)

There will be widespread downed trees and powerlines.  The snow will be heavy and wet.  Combine the winds and we are looking at a mess.  I'll post a snow map this afternoon but in general 

06z NAM snow accumulations (image weatherbell)

I think the heavy wet nature of the snow holds totals down.  Some guidance is crazy; it may be right so I want to take a bit more time to look it over.  Have a good day!

Large Storm to Lash East Coast Midweek- Southern New England Impacts

A snowmaker moving through the Upper Plains and Ohio Valley will meet up with southern stream energy off the North Carolina coast to spawn a large and powerful ocean storm.  While a direct hit is unlikely, it cannot be ruled out yet as the American GFS is showing a foot of fresh snow falling on the region.  Instead strong gusty winds will be a big threat especially SE New England.  Big waves will also pound the beaches for days, further damaging areas struck hard by Sandy in the Mid Atlantic and the Blizzard of 2013 in New England.  Light snow, moderate at times will be possible Wednesday night especially SE MA.  Thursday night will see greater potential for accumulating snow from Boston to Worcester south and east.

Current Conditions/Storm Evolution

Surface

HPC surface chart 521 AM EST

A strong system is producing snow across North Dakota, Southern Canada, into Minnesota.  Low pressure over Oklahoma is also slowly pushing east.  These will combine near the Mid Atlantic Coast.  At the upper levels we still are dealing with an upper level low.  

06z NAM 500 mb vorticity 

Today should feature a bit more sun than the past few days.  There will still be clouds around but temperatures will climb to 40 from Worcester County South and east.  

10z RAP 2 m Temp 2 PM (image weatherbell)

Winds today will be breezy at times out of the northwest

06z NAM 15 hour 10 m wind speed valid 4 PM (image weatherbell)

By tomorrow our 500 mb charts look like this

06z NAM 500 mb vort valid Tuesday 10 am 

Our ULL is still off the New England coast.  This low cannot go anywhere, it is blocked.  This will play a role on Wednesday .  The low will keep the same pattern in place; some sun, mostly clouds.  There will be isolated snow/rain showers due to the instability an ULL creates in the lower atmosphere.  Temperatures tomorrow look like this

00z EPS t 2 m max, Tuesday afternoon (image weatherbell)

At the same time here is the projected surface chart

HPC surface outlook Tuesday 7 PM 

Moving along to Wednesday

06z NAM 500 mb vort valid Wednesday 7 am EST

The ULL backs away slightly and our storm deepens at 500 mb.  It starts to take on a slight negative tilt.  This is important because there is no pure Arctic air mass in the lower 48.  A negatively titled trough will allow the storm to become more intense and thus help create its own cold air.  The projected surface at the same time

HPC surface outlook Wednesday 7 am EST

No doubt this storm slides to the east northeast but the question is how far north will it come?  What type of interaction will the storm have with our ULL and high pressure to our north?  We may see just high winds and high surf Wednesday into Thursday.

06z NAM 10 m winds Thursday 4 am EST (image weatherbell)

These are sustained winds of 25-30 mph.  Wind gusts will be over 40 inland, will approach 50-60 on the Cape.  

06z GFS 900 mb winds, mslp Thursday 7 am (image weatherbell)

This is at 900 mb, or about 3500 feet above the surface.  Those are hurricane force winds across SNE and a battering fetch of winds blowing directly onto the New England shore.  

HPC 5 day precipitation forecast

HPC is still looking at a quarter inch of precipitation for most.  A half inch is creeping towards the Cape and Islands.

Summary

I am more concerned about strong winds than snow at this point.  The GFS, its ensembles, and even the EURO Ensemble is bringing some snow into SNE.  We shall see, what is clear is an impressive coastal storm will be offshore during midweek.  Updates will be issued as needed, have a good day!

Midweek Storm Close Enough to Watch

A large ocean storm will develop mid week but it will be difficult for the storm to affect SNE.  While I cannot rule out light snow for Cape Cod and coastal Southern MA/RI/CT the vast majority of the region will be spared.  

Current Conditions/Short Range Forecast
A stubborn Upper Level Low continues to spin offshore.  The result is clouds and a few light snow showers

941 am NWS Boston radar

The low can be seen on sat and in the upper level charts

12z NAM 500 mb vort from 8 am 

The latest WV

NOAA Water Vapor Sat 915 am

Two weak upper level features are converging in SNE and the result is the light snow.  Temperatures are currently 

9 am 2 m Temps (image weatherbell)

Temperatures today will top in the mid to upper 30's with low 40's possible near the coast

EPS 2 m Max temps Sunday Afternoon (image weatherbell)

Overnight lows will be in the low to mid 20's.  Monday will be much like today although I do not think the snow showers will be an issue tomorrow.  However it will still be mostly cloudy as the ULL struggles to get out of here.  Eventually, by Wednesday the low will kick itself out.  And just off the NC/VA coast we have this

12z NAM 500 mb Vorticity Wednesday 7 PM

Pretty much all of the support is out to sea for this.  Why?  Well a there is a massive atmospheric block.  It is too strong for a New England storm.  The storm track is suppressed to the south.  Look at the current temperatures in the Southeast

2 m temps 9 am (image weatherbell)

When one sees cold like that in Florida its a tall tail sign that the NAO/AO are extremely negative.

Weatherbell AO/NAO time-series

The forecast

GFS NAO forecast (image weatherbell)

With a negative anomaly like that it will be hard to get snow into New England. The negative anomaly is also why we have been unable to kick out the ULL.  So here is what we are looking at Wednesday and Thursday

HPC Day 3 Wednesday 7 am

Thursday

HPC Day 4 Thursday 7 am

The high pressure is in a good spot for inland snows.  It will important to fine tune this as the event comes closer.  A 50 mile jog to the north would bring accumulating precipitation into SNE.  Here is the HPC 5 day precipitation totals

HPC 5 day precipitation totals

Have a good Sunday, we'll talk tomorrow and see if there are any northward trends.

Mix of Sun and Clouds Through the Weekend

The headline is a bit misleading- the weekend is not going to be terrible.  However there will be more clouds than sun for the majority of the time.  Friday looks to be the brightest day of all with a mix of sun and clouds and high temperatures in the low to mid 40's across all of Southern New England.  It would not surprise me if some locations that see more sun than clouds approach 50.

Current Conditions 

HPC 530 am Surface Map

(Note- the Hydrometeorological Prediction Center, HPC, will become the Weather Prediction Center or WPC in the near future)

Surface chart looks alright for the east coast but at 500 mb its a different story

06z NAM 500 mb vort 1 am EST (NCEP)

You can see the closed off contour right over New England.  Luckily there is not much precipitation associated with the low right now

NWS Northeast Radar 618 AM EST

I expect today to be mainly dry, as does the HPC

HPC day 1 precipitation outlook

The cloud cover forecast for early afternoon off the NAM

06z NAM cloud cover projection 1 PM EST (image weatherbell)

And temperatures

10z RAP 2 m Temps 1 PM EST (image weatherbell)

Eastern CT, all of RI, and MA south of Rt 2 all are the best candidates to approach 50.

Weekend Forecast

A few weak low pressure centers will be spawned by the upper level low.  These will be dump rain but could drop a quick shower or snow shower.  Sunday looks most likely to see any precipitation.  Temperatures on both Saturday and Sunday will be in the low to mid 40's.  Total weekend precipitation

HPC Day 1-3 precipitation forecast

Tomorrow morning I will touch on potential for a strong coastal storm next week.  Trends are that there will be a storm off the east coast, but where exactly is the question.  Precipitation type looks to be wet for the coast, white interior.  With the lack of a pure Arctic High to the north (it will be around Hudson Bay, a bit too far north for March) AT THIS TIME I favor a wind whipped rain for Southern New England.  Plenty of time to watch, have a good day!